1. Field of the Invention
The present invention relates to a structure of a transmission comprising a belt-type continuously variable transmission (hereafter referred to as ‘CVT’), which is suitable for a working vehicle.
2. Background Art
A conventional working vehicle, e.g., a truck, includes a belt-type CVT connecting an output shaft of an engine and an input shaft of the transmission such that rotation of the output shaft of the engine is transmitted to its axles and drives them. In this vehicle structure, a sensing mechanism is provided at the CVT and detects rotary speed or load of the engine so as to automatically steplessly reduce/increase the speed reduction ratio according to the increase/decrease of rotary speed of the engine or the decrease/increase of the engine load.
In addition, it is well-known to laterally mount an engine on a vehicle so as to locate its crankshaft perpendicular to the longitudinal direction of the vehicle and in parallel to an input shaft of a transmission, an output shaft of the transmission, and axles. This described vehicle structure especially facilitates interposing a belt-type CVT between the crankshaft of the engine and the input shaft of the transmission because both shafts are parallel to each other. Moreover, the transmission in this vehicle structure may transmit power via economical spur wheels because shafts therein are disposed parallel to one another. Therefore, the vehicle structure is advantageous in contributing to the reduction of assembly and material costs.
An object of the invention is to provide a transmission for a working vehicle that is simplified so that the manufacturing costs can be more and more reduced.
Further, conventional transmissions with differential locking mechanisms provide a shaft for operating the differential locking mechanism that is axially, slidably supported and is disposed parallel to the axles. The differential locking slider is engaged with a fork fixed onto the shaft so as to slide the differential locking slider integrally with the shaft, thereby switching between a differential-locking mode and a differential-unlocking mode.
However, in the above conventional structure, the fork engaged with the differential locking slider is apt to be large, thereby inhibiting miniaturization of the transmission. And, because a space inside of the transmission housing is required for straightly moving such a large fork back and forth at a set stroke to operate the differential locking slider, further miniaturization of the transmission is difficult.